Internal-combustion engine



K. l. CROSSLEY AND W.LE P. WEBB. INTERNAL COMBUSTION ENGINE.

APPLICATION FILED IIIIY 22,19I6.

IIAWMI, mmm Mar. 28, Ism. FIG. E Ig.

STATES PATENT OFFICE.

KENNETH IRWIN CROSSLEY, 0F MANCHESTER, AND WILFRED LE PLASTRIER WEBB,

' 0F HALE,

ENGLAND.

INTERNAL-COMBUSTION ENGINE.

Specification of Letters Patent.

Patented Mar. 28, 1922.

Applicationl filed July 22, 1916. Serial No. 110,667.

To all whom it may conce-m.'

Be it known that we, KENNETH IRWIN CnossLEY and Turman Lr. PLAsTRmR VTiB, both subjects of the King of Great Britain, residing, the former at Crossley Brothers Limited, of Openshaw`r Manchester, inthe county of Lancaster, England, and the latter at Rostrevor, Hale, in the county of Chestel', England, have invented new and useful Improvements in InternalCombustion Engines, of which the following is a specification.

Our invention relates to the kind of internal combustion engine which uses the heavier fuel oils and in which the oil is injected by itself as spray (without the aid of injection air) into the compressed and therefore heated air inthe combustion chamber towards the end of the compression stroke, the air being compressed and therefore heated to such a degree that when the oil is sprayed into the combustion chamber it is ignited.

We are aware that engines of the kind described have previously been started from the cold state by compressing the air usually to about four hundred and fifty pounds, although compression pressures as low as about two hundred and fifty to three hundred pounds per square inch above atmospheric pressure have been proposed, but in order to enable such engines to be started from the cold state, and to vaporize and ignite their oil charges without the aid of externally applied heat, the oil just behind the spraying orificeor orifices has, we believe, during the period in which it is sprayed into the combustion chamber, been subjected to extreme pressure, i. e. about two thousand to six thousand pounds per square inch, so that by the large and sudden drop or pressure be-l tween the two sides of the spraying orifice or orifices, together with the heat of the compressed air into which the injection takes place, the finely atomized oil spray is instantly vaporized and ignited. These extreme pressures of oil injection have been hitherto found necessary.

Our invention is based on the appreciation that (l) these high pressures of oil injection have been required because when oil is injected by itself as spray into heated air for combustion, instantaneous vaporization and mixing with the air are diiiicult to attain and (2) by providing for a prolonged contact of the spray with the heated air, prolonged either in time or distance or both. vaporlzation and mixing can be greatly fa-y cllitated and the certainty of`ignition improved.

It is to be noted that when spray issues from an atomizing orice, the greater the contact with the air the better are both the vaporization and the mixing. Greater contact may arise from a lower velocity of efflux of the spray over a longer period of time. (giving a slower travel) or from the provision of a longer path of travel, or both.

Our invention consists of improvements by means of which we are able to start an engine of this kind from the cold state, and yaporize and ignite its charges without using a lamp, or any form of heat supply except that produced by the work done in compressing the air in the cylinder or combustion chamberLwhilst using lower oil injection pressures and in some cases with lower compression pressures.

In our invention we inject the oil spray into the combustion chamber* at a pressure immediately behind the spraying orifice or orifices of only about one thousand pounds per square inch or even in some cases considerably less. The oil spray may be somewhat coal-ser but there is no objection to this as we depend upon the relatively prolonged j contact of the oil spray ,or vapour with the compression-heated `air in a combustion chamber of specially chosen shape for the efficient vaporizing of the oil'spray for its mixing with the air and for the resulting certainty of ignition of the mixture.

Te construct the combustion chamber in such a manner and of such a shape as to Vpresent .approximately as small a wall surace as possible for containing the air at the end of the compression stroke. This entails a rounded .or approximately spheroidal shape, a part of the end of the piston and any valve or valves required forming portions of the containing walls. This construction ensures that the oil spray or Vapour travels through a considerable distance on its path towards the core of the compressed and thereby heated air in the combustion chamber, it also ensures that the said core yis cooledv as little as possible by the influence 0f the lOWl temperature of the containing walls. `r1`he shape which gives the least surface in proportion to the contained volume is of course a true sphere: but, as vapobriz'ing of the oil spiay is ellected by and in the air in the combustion chamber, it follows that the temperature of the air in the neighbour.- hood of the entering oil spray will be somewhat lowered and that if the combustion chamber is approximately spherical. the hottest zone in the combustion chamber.I at the instant immediately previous to ignition is somewhat .away from the centre of the sphereI in tlie direct-ion opposite to the point where the sprayer is located. As this may tend to make the hottest zone or core ot' the air unduly near` and be adversely atlected by the cold walls on that Side ot' the combustion chamber. we prefer to somewhat counteract this effect by elongating the combustion chamber so that itis of such convenient form or shape as will allow its length in the direction in which the oil is sprayedto be not less and preferably greater than either of its other two dimensions as, for'instance, prolate spheroidal or ovitorm or modifications thereof, all of which forms including. an approximate sphere are herein conveiiiently referred to as approximately spheroidal. g

The combustion chamber is provided with a water jacken-except in such 'places where any aii admission valve or-exhaust valve or starting valve or oil sprayer or cleaning dooi" is placed, and which is not usually water jacketed.

The oil being injected at lower pressures than is usual in engines of the kind describeda simpler and cheaper oil pump and operating gear and oil Vsprayer can be used` and the very small sprayingorifice may be larger vinsiae or if several such orifices be used they may be larger in size o'r less in number and consequently more easily made and less liable to obstruction. Also as with our invention-we can start engines from the cold state when the compression pressure is less-tliaii three hundred pounds per square inch above atmosphere there is .a further advantage that a lower initial pressure may -be ensured when the charge is ignited and consequently the engine may be madeboth 'lighter and cheaper.

In some cases, we prefer toi'educe the size of the inner end `of the engine piston and to arrange for this reduced portion of the piston to enter the combustion chamber, so that by an increase of turbulence the vaporizing-of the oil spray and the mixing of the oil spray or vapour with theair is improved; air towards the end of the compression stroke being` displaced'suddenly from the cylinder into thelcombustion chamber through the space between thereduced end of the piston and the entrance to' the combustion chamber.

Referring now to the accompanying diagrammatic drawings which illustrate certain examples of construction according to our invention Figure l illustrates in sectional elevation, an example of an elongated and .approximately oviformshape of combustion chamber with the fuel oil arranged to be sprayed from its smaller end (as indicated by the dotted lines spreading out from the sprayer) in a mean direction corresponding approximately to the 'major .axis ot the chamber.

Figure Q is a cross section of the same, and shows how in this example the chamber is somewhat flattened in shape. It will be readily understood that just before the piston reaches the end of the compression stroke when the oil spray is being injected, the shape of the chamber in cross section is less flattened and more nearly circular.

Figure 3 -illustrates another example of oviform combustion chamber arranged so as not to give the turbulence effect indicated above.

Figure 4 is a sectional elevation illustrating similar-'parts of the usual type of cold starting heavy oil engine, and in which the oil spray is injected either with or without the aid of highly compressed air.

The oil sprayer valve is indicated at SV, the`spraying orifice at O, the oil' chamber behind the spraying orifceatOC, the combustion chamber at Cy the"piston4 atT', and the reduced portion of the-en'd-f the piston (when used) at T, Any valve used is arranged with its head to form part of the walls of the chamber, .as shown for example at V. The hottest core or zone during spraying is indicated approximately by the space contained within the dotted lines at H.

The same letters indicate similar parts in the different figures.

The elongated and somewhat oviform shape of combustion chamber, as shown in Fig. 1, tends to prevent the hottest zone or core in the combustion chamber (which would nuclei' more ordinary circumstances be at or near the mean centre of the chamber) being so adversely affected by the cooling action of the entering oil spray 'as for it (the hottest zone) to be moved unduly near and be unduly affected by the cooling inluence of the cold walls enclosing the end of the chamber opposite to the oil sprayer, as this might thus tend to lower the temperature of the hottest zone to such an extent as .of the walls of the chamber.

With this somewhat elongated form of combustion chamber, the temperature of the air in the hottest zone towards the end of the compression stroke is higher than it otherwise would be, thev vaporizing of the oil spray and the mixing of the o il spray and vapour with the air between the sprayer and the hottestzone is more eiiicient on account of its longer path through dense hot air, the depth of ,the hottest zone H is greater, and consequently a greater margin of certainty of ignition is secured. With this arrangement a lower compression pressure and temperature can be used lthan would be necessary with a less favourable shape of combustion chamber.

When the engine is being started from the cold state, according to our invention, oil is delivered by any suitable means to the orifice or orifices of the oil sprayer at a pressure of about one thousand pounds per square inch or even considerably less, and at the desired moment immediately begins to issue as spray from the verysmall orifice oroitifices of the sprayer, the spray being then efficiently vaporized during its passage for a substantial distancethrough hot compressed air towards the hottest zone in the combustion chamber (such as forexample at H), and is then ignited by the temperature of the air at or near such hottest zone, and we wish it to be clearly understood that no source of heat is used for4 the purpose of ignition, except that produced by the work done in compressing air in the engine cylinder and combustion chamber.

In Fig. 4 we have shown the usual shape of combustion chamber employed in cold starting heavy oil engines, and it is readily 'seen that the hottest zone or core in this case is very flattened in shape, being somewhat as indicatedat H. llt isnecessarily affected by the close proximity of the cold walls ofv the piston and combustion chamber, and also by the oil spray, sothat the vaporizing and ignition time 'j is extremely short. Unless therefore the oil, on being injected, is instantaneously vaporized as it issues, it will fail to ignite or burn satisfactoril It is for this reason that it has been cdiisi necessary hitherto to subject the oil to pressures of from two thousand to six thousand pounds per square inch immediately behind the spraying orifice ororifices in order to ensure starting. Even with such pressures, owing to the unfavourable conditions just indicated, some of the oil at starting is liable to be de osited on the piston head, either due to t e vaporization being only partial,

or owing to re-condensation taking place, with the result that ignition is sluggish or recarious, and -starting unsatisfactory. his is especlally the case when it is sought to use less than 450 pounds per square inch dered compression pressure in usual engine constructions.

On the other hand, when using approximately spheroidal shapes such as an approximately spherical combustion chamber, we can lwith our invention, start the engine from the cold state, and satisfactorily vaporize, ignite and burn the oil charges with low compression pressures say about three hundred and fifty pounds per square inch, or, if an elongated combustion chamber is used, as we prefer, for instance oviform as illustrated in Fig. 1, wecan start the engine from the cold state and satisfactorily vaporize, ignite and burn the oil charges when using a compression pressure even as low as two hundred and fifty pounds per square inch.

As an example, an oil engine which we have constructed and which we can start from the cold state, according to our invention, has a piston fourteen inches in diameter with a stroke of twenty-three inches, an elongated combustion chamber approxi mately oviform in shape, and a compression pressure of about two hundred and eighty pounds per square inch. This engine can be started by first admitting from a storage.

receiver to the engine cylinder and expanding therein a few charges of compressed air in the well known manner and at apressure of about two hundred to two hundred and fifty pounds per square inch, and in a few cycles the heat due to' the work donein compressing the air in the cylinder during the compression stroke will ignite the heavier oil spray charges of sayy Russian crude oil (having a viscosity of about seventy seconds at seventy degrees Fahrenheit, as determined in the Redwood viscometer), when injected into the combustion chamber towards the end of the compression strokes ofthe engine piston through four small orifices having a total `combined cross sectional area of one-seventeen-hundredth of a square inch,at a pressure immediately behindV the spraying vorifices of about one thousand pounds per square inch, the en-v gine then continuing to work under its own power and vaporize, ignite and burn its charges satisfactorily.

used to obtain the higher temperatures required. Further, the oil injection pressures required to obtain the same atomizatio-n, varywith the degree of viscosity of the oils, but we find it isnot necessary to use oil in jection pressuresappreciably exceeling one thousand pounds per square inch.

In Figs. 1 and 2 we have shown the combus'tion chamber and piston arranged for turbulence utilization, which we sometimes prefer', the end of the piston being reduced in diameter at T, and projecting into the its or core H, but to tend more towards scour.

ing the walls.

Although we, in some cases prefer the utilization of considerable turbulence as indicated, it is not a necessity, and the piston and the combustion chamber may vbe suit.

ably arranged so that no such considerable turbulence takes place, either by omitting the part T', or as shown in Fig. 4;

. In the forms ilustrated, the direction of spraying and major axis,V of an elongated chamber,`when used, are disposed 'at right angles to the axis4 of the cylinder. It is,-

however, to be understood that this may be modified to an desired extent, and the direction of spraying and axis of an elongated chamber may bear any'desiredr'elationship to the axis of the cylinder.

. We also Wish it to be clearly understood that we make nol claim, per se, to the forms of combustion chamber indicated, as we have already described such shapes of combustion chamber, for instance, in our applications for British Letters v2974012 1915 and 2976 of 1915.

This invention may be applied in either two-stroke or four-stroke cycle engines.

Patent No. Y

What we claim and desire to secure by Letters Patent is 1. In an internal combustion engine, the combination with a cylinder and a piston reciprocable Within said cylinder, of acombustion chamber ,oviform ,in` .lg/)ngitudinal section and attened at its sides, said combustion chamber being in communication inlterme'diate the ends of its longitudinal axis with the cylinder, whereby the center 'of the heat Zone in the combustion chamber is disposedat one side of the longitudinal center o f said chamber, and means atA the :smaller` end of the combustion chamber for injecting oil into said.heat zone.

2. In an internal combustion engine, the

combination of a'cylinder, a piston vreciprocabl'e in'said cylinder, a combustion chamber communicating Awith said cylinder, said combustion chamberV being transversely of oblate-spheroidal formation and of smaller diameter at one end than at theother, said combustion chamber communicating intermediate its length With thev cylinder, kand means at the smaller end of the said. combustion chamber for injecting a sprayof oil thereinto in' the direction of its longitudinal axis.

In testimonywhereof We have signed our' names to this specification in theu presence of tWo subscribing witnesses` KENNETH IRWIN CROSSLEY.

WILFRED LE PLASTRIER WEBB.

Witnesses: SAMUEL WALKEY GILLETT, HERBERT RowLANp ABBEY. 

